Contact detection method

Abstract

A control device acquires first detection values related to control of a motor at a plurality of positions on a first path by moving an object or a tool along the first path with the object and the tool prevented from coming into contact with each other, acquires second detection values related to the control of the motor at a plurality of positions on a second path substantially parallel to the first path by moving the object or the tool along the second path to bring the object and the tool into contact with each other, derives a difference value between the first detection value and the second detection value acquired at each of corresponding positions on the first path and the second path, and detects contact between the tool and the object based on changes in the difference values derived for the plurality of positions.

What is claimed is: 
     
         1 . A contact detection method for detecting contact between a tool attached to a spindle and an object, the contact detection method comprising:
 acquiring first detection values related to control of a motor included in a feed mechanism at a plurality of positions on a first path by moving the object or the tool along the first path with the object and the tool prevented from coming into contact with each other;   acquiring second detection values related to the control of the motor included in the feed mechanism at a plurality of positions on a second path substantially parallel to the first path by moving the object or the tool along the second path to bring the object and the tool into contact with each other;   deriving a difference value between the first detection value and the second detection value acquired at each of corresponding positions on the first path and the second path; and   detecting contact between the tool and the object based on changes in the difference values derived for the plurality of positions.   
     
     
         2 . The contact detection method according to  claim 1 , wherein
 each of the first detection value and the second detection value contains a fluctuation component generated by mechanical resistance of the feed mechanism.   
     
     
         3 . The contact detection method according to  claim 1 , wherein
 a movement speed when acquiring the first detection values and a movement speed when acquiring the second detection values are equal to each other.   
     
     
         4 . The contact detection method according to  claim 1 , wherein
 the second path ends before a position corresponding to an end position of the first path.   
     
     
         5 . The contact detection method according to  claim 1 , wherein
 when the object or the tool is moved along the second path substantially parallel to the first path and the second detection value exceeds a threshold for termination of movement, the movement along the second path is terminated.